Canon EOS Rebel T1i EOS REBEL T1i/EOS 500D Instruction Manual - Page 186

3 Custom Function SettingsN C.Fn-6 Highlight tone priority 0: Disable 1: Enable Improves the highlight detail. The dynamic range is expanded from the standard 18% gray to bright highlights. The gradation between the grays and highlights becomes smoother. With setting 1, noise in the shadow areas may be slightly more than usual. With setting 1, the settable ISO speed range will be 200 - 3200. Also, the icon will be displayed on the LCD monitor and in the viewfinder when highlight tone priority is enabled. C.Fn-7 Auto Lighting Optimizer If the images comes out dark or the contrast is low, the brightness and contrast are corrected automatically. The settings made with the camera can be reflected in RAW images when the images are processed with Digital Photo Professional (provided software). 0: Standard 1: Low 2: Strong 3: Disable Depending on the shooting conditions, noise might increase. This function will not work if manual exposure or bulb exposure has been set. In the Basic Zone modes, [Standard] is set automatically. 186 B